We will study the synthesis of histone mRNA in a cell-free system. In addition to transcription, assayed by hybridization to plasmid DNA, we will study capping, methylation and endonucleolytic cleavage of the RNA and its eventual transport to the cytoplasm. The control of histone mRNA synthesis will be studied in synchronized mouse myeloma cells and using the cell-free system, we will purify components necessary for histone mRNA synthesis and reproduce the control in vitro. The same approach will be taken in normal human diploid cells to ascertain the difference between the normal and tumor cell and the changes which take place as the cells age.